I know that many experienced trainers, trainees, athletes, strength and conditioning specialist coaches, etc. will say that getting the best results from any kind of training ultimately comes down to trial and error. However, The problem I have with trial and errors is not the obtained solution, but the time (multiple trials) and the errors.
In many situations we cannot afford the time needed to make a sufficients amount of trials and we cannot afford the errors in some cases (errors that lead to injuries or overtraining). The cost of trials and errors can be too high in a lot of cases. Though, I understand that to a extent every individual is different and therefore each individual needs to do some trial and error in order to figure out what works for himself or herself.
So, what I am wondering is how is one supposed to do trial and error in the most time-efficient manner possible so that one doesn’t end up wasting so much time in making very little to no progress in their training? For example, when a lot of guys typically ask why they are not building enough muscle even though they have been working out hard and consistently with compound movements for about 6 months then a typical response would be that they have to figure it out themselves on what they need to change through trial and error including: eat more, eat less, not enough intensity in the workout, too much intensity, not enough sets in the workout, too many sets in a workout, or too many exercises, etc.
However, in a case like this there would seem to be so many factors to experiment with and in so many ways that it may take person an indefinite amount of months figure out the solution if he goes through trial and error with pure instinct. Also what about recovering from overtraining with resistance training? For instance, when someone complains that they are overtraining or overreaching, then a typical response would be that he or she needs to figure it out themselves through trial and error on what they need to do to fix that problem.
Yet again, if that person tries to figure it out through trial and error then he or she would have to go to through a myriad of factors and ways in order to come up with a solution to overtraining such as: getting more sleep, getting less sleep, eating more of the right kinds of foods, eating less junk food or even less of the right kinds of foods, exactly how many stressors need to be eliminated from your life, accurately finding how much volume needs to be reduced or if it needs to be reduced at all, precisely how much intensity needs to reduce or if the intensity needs to be reduced at all, more rest days, less rest days, reducing the number of exercise or if any exercises need to be reduced at all, etc. In such a case, it would seem like it could take several months to figure out what the cause to his or her overtraining was if he or she didn’t have a qualified training expert or coach.
So how does an athlete or regular trainee go about trial and error without wasting so many months or even years of self-experimentation?